DOCSLIB.ORG

The Incredible Lightness of Being Methane-Fuelled: Stable Isotopes Reveal Alternative Energy Pathways in Aquatic Ecosystems and Beyond

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Incredible Lightness of Being Methane-Fuelled: Stable Isotopes Reveal Alternative Energy Pathways in Aquatic Ecosystems and Beyond View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Frontiers - Publisher Connector REVIEW published: 11 February 2016 doi: 10.3389/fevo.2016.00008 The Incredible Lightness of Being Methane-Fuelled: Stable Isotopes Reveal Alternative Energy Pathways in Aquatic Ecosystems and Beyond Jonathan Grey * Lancaster Environment Centre, Lancaster University, Lancaster, UK We have known about the processes of methanogenesis and methanotrophy for over 100 years, since the days of Winogradsky, yet their contributions to the carbon cycle were deemed to be of negligible importance for the majority of that period. It is only Edited by: in the last two decades that methane has been appreciated for its role in the global Jason Newton, carbon cycle, and stable isotopes have come to the forefront as tools for identifying Scottish Universities Environmental Research Centre, UK and tracking the fate of methane-derived carbon (MDC) within food webs, especially Reviewed by: within aquatic ecosystems. While it is not surprising that chemosynthetic processes David Bastviken, dominate and contribute almost 100% to the biomass of organisms residing within Linköping University, Sweden Blake Matthews, extreme habitats like deep ocean hydrothermal vents and seeps, way below the reach Eawag: Swiss Federal Institute of of photosynthetically active radiation, it is perhaps counterintuitive to find reliance upon Aquatic Science and Technology, MDC in shallow, well-lit, well-oxygenated streams. Yet, apparently, MDC contributes to Switzerland varying degrees across the spectrum from point sources to extremely diffuse sources. *Correspondence: Jonathan Grey Certainly a good proportion of the evidence for MDC contributing to freshwater food [email protected] webs comes from somewhere in the middle of that spectrum; from studies of seasonally stratifying lakes (mono- or dimictic) wherein, there is a defined gradient or boundary Specialty section: This article was submitted to at which anoxic meet oxic conditions and consequently allows for close coupling of Population Dynamics, methanogenesis and methanotrophy. However, even seemingly well-mixed (polymictic) a section of the journal Frontiers in Ecology and Evolution lakes have a contribution of MDC contributing to the benthic biomass, despite an almost continual supply of photosynthetic carbon being delivered from the surface. Aside Received: 31 October 2015 Accepted: 25 January 2016 from the fundamental importance of identifying the carbon sources fuelling biomass Published: 11 February 2016 production, stable isotopes have been integral in the tool box of palaeolimnologists Citation: seeking to identify how contributions from methane have waxed and waned over time. Grey J (2016) The Incredible Lightness of Being Methane-Fuelled: Stable Here, we synthesize the current state of knowledge in the use of stable isotopes to trace Isotopes Reveal Alternative Energy MDC in primarily freshwater ecosystems. Pathways in Aquatic Ecosystems and Beyond. Front. Ecol. Evol. 4:8. Keywords: methanotrophy, chironomids, zooplankton, carbon, food webs, greenhouse gas, biogeochemical doi: 10.3389/fevo.2016.00008 cycling, trophic transfer Frontiers in Ecology and Evolution | www.frontiersin.org 1 February 2016 | Volume 4 | Article 8 Grey Identifying and Tracking Methane in Food Webs A BRIEF SYNOPSIS ON THE GLOBAL routes by which CH4 produced in anoxic freshwater sediments IMPORTANCE OF METHANE IN AQUATIC may either by-pass or become incorporated into food webs is SYSTEMS, AND PARTICULARLY IN shown in Figure 1. FRESHWATERS COULD A METHANE PATHWAY BE The global carbon cycle was considered, until relatively recently, IMPORTANT TO SECONDARY to be solely the flux and storage of carbon between the PRODUCTION IN FOOD WEBS? atmosphere, and terrestrial and oceanic pools. Within the total carbon budget, it has been noted that despite their relatively Anoxic water and sediments are typically rich in organic small area, inland freshwaters make a considerable contribution matter compared to the overlying oxic water, and anoxic to the global methane (CH4) budget with emissions of CH4 from metabolism may account for a substantial part (20–60%) of the freshwaters being at least comparable to the terrestrial CH4 sink carbon metabolism and the heterotrophic microbial production (Battin et al., 2009). However, there is a considerable bias toward within freshwater environments (Hessen and Nygaard, 1992). data from lakes and other wetlands, and the role of rivers remains Methanogenesis in lakes has been reported corresponding to 30– poorly defined (Bastviken et al., 2011). Emissions of CH4 may be 80% of the anaerobic mineralization in waters and sediments small in terms of carbon, but one must consider that CH4 is a (Bastviken, 2009). While seasonal variability in CH4 oxidation is more potent greenhouse gas than CO2 over century time scales; known to be considerable, especially in dimictic lakes, between (Bastviken et al., 2011) estimated that global CH4 emissions 30–94% of the CH4 reaching oxygenated layers is reputedly expressed as CO2 equivalents correspond to at least 25% of the oxidized (Casper et al., 2000; Morana et al., 2015). In essence estimated terrestrial greenhouse gas sink. Our understanding of then, CH4 is a major product of the C mineralization in the global carbon cycle will only be complete if we include the lakes, and a large proportion may be converted to microbial flux of carbon through inland freshwaters (Cole et al., 2007; biomass equivalent in some instances to the total C fixation by Battin et al., 2009; Trimmer et al., 2012) getting to grips with heterotrophic bacteria and a significant proportion of primary methane-fuelling of food webs is an interesting and important production (Hessen and Nygaard, 1992; Bastviken et al., 2003). component of this. Indeed, (Cole, 2013) noted that “the role of Again, data from rivers are lacking, but across 15 rivers, in late methane in supporting food webs in lakes, and perhaps even summer, i.e., when one might expect the greatest contribution beyond their shores, has come as a surprise” and that “the from photosynthesis, (Shelley et al., 2014) conservatively notion that lake methane partially supports higher organisms in calculated that net methanotrophy was equivalent to between 1 surrounding terrestrial environments fundamentally changes our and 46% of benthic net photosynthetic production within the understanding of how aquatic food webs work.” gravel beds of chalkstreams. Couple this to the apparently high Methanogenesis is a universal terminal degradation process (50%) carbon conversion efficiency of methanotrophs (relative of organic matter in anoxic aquatic sediments when inorganic to 10–30%, typical for bacteria in detrital-based food webs), oxidants such as nitrate, ferric iron, or sulfate are depleted regardless of marked spatial and temporal changes in ambient (Conrad, 2005). Hence, in marine systems where there is methane concentration, and it suggests that methanotrophs can typically a high concentration of sulfate, the sulfur cycle sustain net production throughout the year (Trimmer et al., tends to dominate chemosynthesis, but in freshwaters where 2015). sulfate concentrations are typically lower (Hobbie, 1988) then The importance of a CH4 pathway to food webs might yet methanogenesis dominates. Stable isotopes have been an increase further under climate change. Increases in temperature incredibly useful tool in the identification and quantification forecast for the coming decades may have profound implications of methanogenic and methanotrophic pathways (Conrad, 2005) for the cycling of carbon in aquatic ecosystems due to the and further identifying the constituents of the complex microbial differential temperature dependencies of carbon fixation by community that is actively involved via stable isotope probing gross primary production (GPP) and carbon mineralization (SIP; e.g., He et al., 2012), but those aspects are not the focus of by ecosystem respiration (ER). For example, (Yvon-Durocher this review. Methane may be lost directly from the system via et al., 2010) showed that warming of 4◦C reduced the carbon ebullition or the recently hypothesized micro-bubble pathway, sequestration capacity of freshwater mesocosms by 13%, shifting stochastic processes notoriously difficult to quantify (Prairie and them toward net heterotrophy (i.e., net sources of CO2 to del Giorgio, 2013) or be effectively “piped” to the surface via the atmosphere) because ER responded more strongly to plants (Bergstrom et al., 2007; Sanders et al., 2007). Alternatively, temperature than GPP. They also found that methanogenesis or in addition, it may subsequently serve as an energy and C responded even more strongly than ER or GPP, with 20% more ◦ source for methanotrophs (methane oxidizing bacteria; MOB), of the GPP being accounted for by CH4 emissions with 4 C typically at oxic-anoxic boundaries (if anaerobic CH4 oxidation of warming (Yvon-Durocher et al., 2011). Benthic community is excluded) in the sediment, or in the water column (Kankaala structure and how that contributes to a host of ecosystem et al., 2007). It is essentially from this point in the cycle that processes, including microbial and macrofaunal decomposition stable isotopes have been key in tracing the use of methane- rates, was also clearly affected by such warming (Dossena et al., derived carbon (MDC) into, and through, food webs, particularly 2012). If it is assumed that delivery of organic matter does
Load more

Recommended publications
  • What Happened When Wolves Were Reintroduced to Yellowstone Park?
    Trophic Cascades: What Happened When Wolves Were Reintroduced to Yellowstone Park? Lesson Question How did the reintroduction of wolves into Yellowstone Park affect the other animals and plants in the ecosystem? Lesson Tasks Students analyze data to determine the effect of wolves on Yellowstone’s elk population, on the plants that elk graze on, and on the animals that compete with elk for food. They write a report describing how the reintroduction of wolves has created a trophic cascade—not just a few direct changes in one food chain, but a series of indirect changes throughout the food web. Standards • HS-LS2-2 Ecosystems: Interactions, Energy, and Dynamics NGSS Science and Engineering Practices • Constructing Explanations and Designing Solutions • Engaging in Argument from Evidence • Evaluate the claims, evidence, and reasoning behind currently accepted explanations or solutions to determine the merits of arguments. NGSS Disciplinary Core Ideas • LS2.C: Ecosystem Dynamics, Functioning and Resilience • ETS1.B: Developing Possible Solutions Crosscutting Concepts • Stability and Change, Patterns Connections to Nature of Science • Scientific Knowledge is open to revision in light of new evidence. • Most scientific Knowledge is quite durable, but is, in principle, subject to change based on new evidence and/or reinterpretation of existing evidence. Trophic Cascades: What Happened When Wolves Were Reintroduced to Yellowstone Park? TABLE OF CONTENTS OVERVIEW ........................................................... 3 INVESTIGATION ...............................................
    [Show full text]
  • Evidence for Ecosystem-Level Trophic Cascade Effects Involving Gulf Menhaden (Brevoortia Patronus) Triggered by the Deepwater Horizon Blowout
    Journal of Marine Science and Engineering Article Evidence for Ecosystem-Level Trophic Cascade Effects Involving Gulf Menhaden (Brevoortia patronus) Triggered by the Deepwater Horizon Blowout Jeffrey W. Short 1,*, Christine M. Voss 2, Maria L. Vozzo 2,3 , Vincent Guillory 4, Harold J. Geiger 5, James C. Haney 6 and Charles H. Peterson 2 1 JWS Consulting LLC, 19315 Glacier Highway, Juneau, AK 99801, USA 2 Institute of Marine Sciences, University of North Carolina at Chapel Hill, 3431 Arendell Street, Morehead City, NC 28557, USA; [email protected] (C.M.V.); [email protected] (M.L.V.); [email protected] (C.H.P.) 3 Sydney Institute of Marine Science, Mosman, NSW 2088, Australia 4 Independent Researcher, 296 Levillage Drive, Larose, LA 70373, USA; [email protected] 5 St. Hubert Research Group, 222 Seward, Suite 205, Juneau, AK 99801, USA; [email protected] 6 Terra Mar Applied Sciences LLC, 123 W. Nye Lane, Suite 129, Carson City, NV 89706, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-907-209-3321 Abstract: Unprecedented recruitment of Gulf menhaden (Brevoortia patronus) followed the 2010 Deepwater Horizon blowout (DWH). The foregone consumption of Gulf menhaden, after their many predator species were killed by oiling, increased competition among menhaden for food, resulting in poor physiological conditions and low lipid content during 2011 and 2012. Menhaden sampled Citation: Short, J.W.; Voss, C.M.; for length and weight measurements, beginning in 2011, exhibited the poorest condition around Vozzo, M.L.; Guillory, V.; Geiger, H.J.; Barataria Bay, west of the Mississippi River, where recruitment of the 2010 year class was highest.
    [Show full text]
  • CHAPTER 5 Ecopath with Ecosim: Linking Fisheries and Ecology
    CHAPTER 5 Ecopath with Ecosim: linking fi sheries and ecology V. Christensen Fisheries Centre, University of British Columbia, Canada. 1 Why ecosystem modeling in fi sheries? Fifty years ago, fi sheries science emerged as a quantitative discipline with the publication of Ray Beverton and Sidney Holt’s [1] seminal volume On the Dynamics of Exploited Fish Populations. This book provided the foundation for how to manage fi sheries and was based on detailed, mathe- matical analyses of the dynamics of individual fi sh populations, of how they grow and how they are affected by fi shing. Fisheries science has developed and matured since then, and remarkably much of what has been achieved are modifi cations and further developments of what Beverton and Holt introduced. Given then that fi sheries science has developed to become one of the most data-rich, quantita- tive fi elds in ecology [2], how well has it fared? We often see fi sheries issues in the headlines and usually in a negative context and there are indeed many threats to the sustainability of ocean resources [3]. Many, judging not the least from newspaper headlines, consider fi sheries manage- ment a usual suspect in connection with fi sheries collapses. This may lead one to suspect that there is a problem with the science, but I hold this to be an erroneous conclusion. It should be stressed that the main problem is not to be found in the computational aspects of the science, but rather in how management advice actually is implemented in praxis [4]. The major force in fi sh- eries throughout the world is excessive fi shing capacity; the days with unexploited resources and untapped oceans are over [5], and the fi shing industry is now relying heavily on subsidies to keep the machinery going [6].
    [Show full text]
  • OCN 201 Spring 2011 Exam 3 (75 Pts) True Or False (1 Pt Each)
    Name:________________________ Exam: ____A____ ID: ______________________________ OCN 201 Spring 2011 Exam 3 (75 pts) True or False (1 pt each). A = TRUE; B = FALSE 1. According to the “serial endosymbiosis theory”, prokaryotes developed when eukaryotes lost their organelles. 2. The aphotic zone of the ocean is in the epipelagic. 3. Amino acids (one of the building blocks of life) have been found in meteorites. 4. Bioluminescence occurs only in the deep sea. 5. Phytoplankton are photoautotrophs. 6. Marine snow is a source of organic carbon to the deep sea. 7. Tropical oceans have very low productivity for most of the year because they frequently mix below the critical depth year-round. 8. Larger organisms are more abundant than smaller ones in the ocean. 9. Ctenophores (comb jellies) propel themselves by pulsing their bell, just like jellyfish. 10. Corals have only one opening to their digestive cavity. 11. Many animals in the very deep sea are red or black. 12. The “deep scattering layer” moves toward the sea surface during the day. 13. In fisheries, the maximum sustainable yield is the amount of fish that must be caught to keep up with the current rate of inflation. 14. Geological evidence indicates that life on earth began at least 3.5 billion years ago. 15. Light and nutrients are the two main things limiting primary productivity in the ocean. 16. Areas of the ocean with upwelling tend to have high productivity. 17. Some bacteria are photoautotrophs. p. 1 of 6 18. Nudibranchs are a type of flatworm 19. Whales are nekton. 20.
    [Show full text]
  • Chapter 36D. South Pacific Ocean
    Chapter 36D. South Pacific Ocean Contributors: Karen Evans (lead author), Nic Bax (convener), Patricio Bernal (Lead member), Marilú Bouchon Corrales, Martin Cryer, Günter Försterra, Carlos F. Gaymer, Vreni Häussermann, and Jake Rice (Co-Lead member and Editor Part VI Biodiversity) 1. Introduction The Pacific Ocean is the Earth’s largest ocean, covering one-third of the world’s surface. This huge expanse of ocean supports the most extensive and diverse coral reefs in the world (Burke et al., 2011), the largest commercial fishery (FAO, 2014), the most and deepest oceanic trenches (General Bathymetric Chart of the Oceans, available at www.gebco.net), the largest upwelling system (Spalding et al., 2012), the healthiest and, in some cases, largest remaining populations of many globally rare and threatened species, including marine mammals, seabirds and marine reptiles (Tittensor et al., 2010). The South Pacific Ocean surrounds and is bordered by 23 countries and territories (for the purpose of this chapter, countries west of Papua New Guinea are not considered to be part of the South Pacific), which range in size from small atolls (e.g., Nauru) to continents (South America, Australia). Associated populations of each of the countries and territories range from less than 10,000 (Tokelau, Nauru, Tuvalu) to nearly 30.5 million (Peru; Population Estimates and Projections, World Bank Group, accessed at http://data.worldbank.org/data-catalog/population-projection-tables, August 2014). Most of the tropical and sub-tropical western and central South Pacific Ocean is contained within exclusive economic zones (EEZs), whereas vast expanses of temperate waters are associated with high seas areas (Figure 1).
    [Show full text]
  • Pesticide Use Harming Key Species Ripples Through the Ecosystem Regulatory Deficiencies Cause Trophic Cascades That Threaten Species Survival Boulder Creek
    Pesticide Use Harming Key Species Ripples through the Ecosystem Regulatory deficiencies cause trophic cascades that threaten species survival Boulder Creek, Boulder, Colorado © Beyond Pesticides DREW TOHER stabilizing the water table, and both worked in tandem to provide cool, deep, shaded water for native fish. espite a growing body of scientific literature, complex, ecosystem-wide effects of synthetic When a predator higher up on the food chain is eliminated, pesticides are not considered by the U.S. Envi- that predator’s prey is released from predation, often causing ronmental Protection Agency (EPA). Beyond a trophic cascade that throws the ecosystem out of balance. direct toxicity, pesticides can significantly reduce, It is not always the top-level predator that creates a trophic Dchange the behavior of, or destroy populations of plants cascade. The loss or reduction of populations at any trophic and animals. These effects can ripple up and down food level—including amphibians, insects, or plants—can result chains, causing what is known as a trophic cascade. in changes that are difficult to perceive, but nonetheless A trophic cascade is one easily-understood example equally damaging to the stability and long-term health of of ecosystem-mediated pesticide effects. an ecosystem. Salient research on the disruptive, cascading effects that pesticides have at the ecosystem level must lead In determining legal pesticide use patterns that protect regulators to a broader consideration of the indirect impacts ecosystems (the complex web of organisms in nature) EPA caused by the introduction of these chemicals into complex requires a set of tests intended to measure both acute and living systems.
    [Show full text]
  • Herbivore Intraspecific Variation and Evolutionary Divergence Drive Trophic Cascade Strength
    bioRxiv preprint doi: https://doi.org/10.1101/722140; this version posted August 1, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC 4.0 International license. 1 1 Herbivore intraspecific variation and evolutionary divergence drive trophic cascade strength 2 3 Arnaud Sentis1,4*, Raphaël Bertram1, Nathalie Dardenne1, Jean-Christophe Simon2, Alexandra Magro1, 4 Benoit Pujol3, Etienne Danchin1‡, and Jean-Louis Hemptinne1‡ 5 1 UMR-5174; EDB (Laboratoire Évolution & Diversité Biologique); CNRS, Université Toulouse III- 6 Paul Sabatier, IRD, 118 route de Narbonne, F-31062 Toulouse Cedex 9, France. 7 2 UMR 1349; IGEPP (Institut de Génétique, Environnement et Protection des Plantes); INRA, 8 Agrocampus Ouest,Université Rennes 1; Domaine de la Motte B.P. 35327, F-35653 Le Rheu cedex, 9 France. 10 3PSL Université Paris: EPHE-UPVD-CNRS, USR 3278 CRIOBE, Université de Perpignan, 52 Avenue 11 Paul Alduy, 66860 Perpignan Cedex, France. 12 4IRSTEA, Aix Marseille Univ., UMR RECOVER, 3275 route Cézanne, 13182 Aix-en-Provence, 13 France. 14 ‡These authors contributed equally to this work. 15 *Corresponding author: Arnaud Sentis. IRSTEA, Aix Marseille Univ., UMR RECOVER, 3275 route 16 Cézanne, 13182 Aix-en-Provence, France. 17 E-mail: [email protected]; phone: +33 4 42 66 99 05. 18 19 Abstract 20 Trophic cascades—the indirect effect of predators on non-adjacent lower trophic levels—are important 21 drivers of the structure and dynamics of ecological communities.
    [Show full text]
  • Key Features and Context-Dependence of Fishery-Induced Trophic Cascades
    Review Key Features and Context-Dependence of Fishery-Induced Trophic Cascades ANNE K. SALOMON,∗† SARAH K. GAICHAS,‡ NICK T. SHEARS,∗ JENNIFER E. SMITH,§ ELIZABETH M. P. MADIN,∗†† AND STEVEN D. GAINES∗†† ∗Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA 93106-6150, U.S.A. †School of Resource and Environmental Management, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada, email [email protected] ‡National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Center, 7600 Sand Point Way NE, Seattle, WA 98115, U.S.A. §Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, U.S.A. ††Department of Ecology Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106-9610, U.S.A. Abstract: Trophic cascades triggered by fishing have profound implications for marine ecosystems and the socioeconomic systems that depend on them. With the number of reported cases quickly growing, key features and commonalities have emerged. Fishery-induced trophic cascades often display differential response times and nonlinear trajectories among trophic levels and can be accompanied by shifts in alternative states. Furthermore, their magnitude appears to be context dependent, varying as a function of species diversity, regional oceanography, local physical disturbance, habitat complexity, and the nature of the fishery itself. To conserve and manage exploited marine ecosystems,
    [Show full text]
  • Trophic Cascade Modelling in Bathyal Ecosystems
    Doctoral Thesis Trophic cascade modelling in bathyal ecosystems Author: Supervisor: Valeria Mamouridis Dr. Francesc Maynou A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in the Bio-Economic Modelling Research Group Dept. de Recursos Marins Renovables (ICM-CSIC) and the Dept. de Ingenier´ıa Hidr´aulica, Mar´ıtima y Ambiental (EHMA-UPC) February 2015 Declaration of Authorship I, Valeria Mamouridis , declare that this thesis titled, ’Trophic cascade modelling in bathyal ecosystems’ and the work presented in it are my own. I confirm that: ∎ This work was done wholly or mainly while in candidature for a research degree at this University. ∎ Where any part of this thesis has previously been submitted for a degree or any other qualification at this University or any other institution, this has been clearly stated. ∎ Where I have consulted the published work of others, this is always clearly attributed. ∎ Where I have quoted from the work of others, the source is always given. With the exception of such quotations, this thesis is entirely my own work. ∎ I have acknowledged all main sources of help. ∎ Where the thesis is based on work done by myself jointly with others, I have made clear exactly what was done by others and what I have contributed myself. Signed: Date: iii INSTITUT DE CI ENCIES` DEL MAR (CSIC) UNIVERSITAT POLIT ECNICA` DE CATALUNYA Abstract Dept. de Ingenier´ıa Hidr´aulica, Mar´ıtima y Ambiental (EHMA-UPC) Dept. de Recursos Marins Renovables (ICM-CSIC) Doctor of Philosophy Trophic Cascade Modelling in Bathyal Ecosystems by Valeria Mamouridis In this Ph.D.
    [Show full text]
  • Ecopath with Ecosim: a User's Guide
    ECOPATH WITH ECOSIM: A USER’S GUIDE by Villy Christensen, Carl J. Walters and Daniel Pauly October 2000 Edition Fisheries Centre University of British Columbia Vancouver, Canada and International Center for Living Aquatic Resources Management Penang, Malaysia No fish is an island… Christensen, V, C.J. Walters and D. Pauly. 2000. Ecopath with Ecosim: a User’s Guide, October 2000 Edition. Fisheries Centre, University of British Columbia, Vancouver, Canada and ICLARM, Penang, Malaysia. 130 p. 2 TABLE OF CONTENTS 1. ABSTRACT...................................................................................................................................... 7 2. INTRODUCTION ............................................................................................................................. 7 2.1 General conventions........................................................................................................................................8 2.2 How to obtain the Ecopath with Ecosim software...........................................................................................9 2.3 Software support, copyright and liability ........................................................................................................9 2.4 Installing and running Ecopath with Ecosim...................................................................................................9 2.5 Previous versions ............................................................................................................................................9
    [Show full text]
  • Predation on Mutualists Can Reduce the Strength of Trophic Cascades
    Ecology Letters, (2006) 9: 1173–1178 doi: 10.1111/j.1461-0248.2006.00967.x IDEA AND PERSPECTIVE Predation on mutualists can reduce the strength of trophic cascades Abstract Tiffany M. Knight,1* Jonathan M. Ecologists have put forth several mechanisms to predict the strength of predator effects Chase,1 Helmut Hillebrand2 and on producers (a trophic cascade). We suggest a novel mechanism – in systems in which Robert D. Holt3 mutualists of plants are present and important, predators can have indirect negative 1 Department of Biology, effects on producers through their consumption of mutualists. The strength of predator Washington University in St effects on producers will depend on their relative consumption of mutualists and Louis, St Louis, MO 63130, USA antagonists, and on the relative importance of each to producer population dynamics. In 2Institute for Botany, University a meta-analysis of experiments that examine the effects of predator reduction on the of Cologne, Cologne, Germany 3 pollination and reproductive success of plants, we found that the indirect negative effects Department of Zoology, University of Florida, of predators on plants are quite strong. Most predator removal experiments measure the Gainesville, FL 32611, USA strength of predator effects on producers through the antagonist pathway; we suggest *Correspondence: E-mail: that a more complete understanding of the role of predators will be achieved by [email protected] simultaneously considering the effects of predators on plant mutualists. Keywords Food web, indirect effects, meta-analysis, pollination success, predator removal, trophic cascade. Ecology Letters (2006) 9: 1173–1178 Ecologists have long recognized the importance of pred- than terrestrial ones (reviewed in Chase 2000; Shurin et al.
    [Show full text]
  • Ripple Et Al in Press.Pdf
    CHAPTER 9 LARGE PREDATORS, DEER, AND TROPHIC CASCADES IN BOREAL AND TEMPERATE ECOSYSTEMS William J. Ripple, Thomas P. Rooney, and Robert L. Beschta In press (expected publication late 2009) in: John Terborgh and James A. Estes (eds.) Trophic Cascades. Island Press, Washington D.C. Historically, humans have modified many boreal and temperate ecosystems by decimating native animal populations and often substituting domesticated stock, thereby influencing food webs and simplifying interactions among species. Large predators, especially, have been subject to worldwide persecution. The profound ecological implications of losing top predators are only now beginning to be understood. Across a variety of environments, predator extirpation can lead via trophic cascades to habitat degradation at multiple trophic levels, species loss, and even ecosystem collapse (Terborgh et al. 1999; Ray et al. 2005). In the 1800s and early 1900s, grey wolves (Canis lupus) and other large predators were the target of widespread eradication efforts throughout much of the United States (Boitani 2003). Extirpation of these predators and subsequent deer irruptions (abrupt population rise) generally occurred earlier in the eastern United States (U.S.) than in the West. The last wolves and cougars (Puma concolor) were killed by the 1880s in New York state and deer subsequently irrupted in the 1890s. By the early 1900s, deer irruptions also occurred in Michigan, Pennsylvania, and Wisconsin (Leopold et al. 1947). In western states, the fate of the wolf was sealed in 1915 when the U.S. Congress authorized eliminating any remaining wolves and other large predators. As part of this program, the United States Biological Survey systematically killed wolves, effectively extirpating them from the western United States by the 1930s.
    [Show full text]